program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  n, k, i, a, b, c:integer;
  H:real;
begin
  readln(n);
  readln(k);
  a:=1;
  b:=1;
  c:=1;
  for i:=1 to n do
    a:=a*i;
  for i:=1 to k do
    b:=b*i;
  for i:=1 to n-k do
    c:=c*i;
  H:=a/b;
  H:=H/c;
  writeln(H:0:0);
  readln;
end.
